Diagnosing Engine Problems

We've all seen TV shows like CSI, NCIS, and other shows in which a mystery must be solved using forensic evidence.

But what happens when a problem appears in our automobiles? Sure you can take it to the mechanic, but how do they know what needs to be repaired if it isn't obvious?

The average automobile is made up of 15,000 to 20,000 parts and pieces. Yes, that's right. From the tiniest of screws to large and complex wiring systems, cars have never been more advanced and technologically challenging as they are today.

Thirty years ago finding and fixing a car problem was easier as there were less components and the systems were easier to diagnose.

Today though, all vehicles use computer and software technology that make it much easier to diagnose and fix problems so that a problem does not continually reappear.

For example, your car's check engine light comes on yet you don't notice anything out of the ordinary. If the car's more than a few years old, do you have it checked out? Do you take it to the garage only to find that it's a minor problem or a malfunction that can be cleared without incident?

Once a problem is diagnosed, how do we know that it's the real problem and not just a symptom of a related problem?

In the early 1980's, the SAE (Society of Automotive Engineers) developed a universal design for monitoring system malfunctions in your car and it's called the On-board diagnostic system (clever).

These systems became mandatory on all cars in 1996.
If you haven't seen the way they work, the next time your car's check engine light comes on, ask the mechanic to let you watch the diagnostics.

When a problem occurs within your car that's part of a system that's monitored, the diagnostic system sends a code to the on board computer that tells the mechanic what has malfunctioned or in what system the problem is.

The mechanic usually has a hand held device with a wire on it that he plugs into a port under the dashboard that reads the code that's now stored in the computer. Depending on the problem, there may be one or more codes as many components work together and a failure in one can lead to trouble in another.

The mechanic finds a P0171 code. What does it mean? An oxygen sensor detected a lean condition (too much oxygen in the exhaust).

Using the related link below, you can find out what the probable cause is and most likely repair is for any fault code that your car spits out.

Now, although you probably won't have the equipment to be able to read the codes, you can ask the mechanic for the codes that were generated and look up the problem and solution yourself.

It's almost like double checking your personal physician, but for the car!

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